Tidal Effects on Dissolved Organic Matter Dynamics in a Brackish Water Front Adjacent to Yangtze River Estuary

Water, Год журнала: 2025, Номер 17(2), С. 226 - 226

Опубликована: Янв. 15, 2025

A brackish water front, where river meets seawater, is a hotspot for biogeochemical processes. In this study, we examined the quantity and composition of dissolved organic matter (DOM) over 24 h tidal cycle at front near Yangtze River estuary. Utilizing elemental analysis, fluorescence ultraviolet spectroscopy, ultra-high-resolution mass spectrometry, observed rapid fluctuations in DOM throughout cycle. The carbon (DOC) total nitrogen (TN) concentrations ranged from 0.70 to 1.5 mg/L 0.43 0.94 mg/L, respectively. Water samples during low tide exhibited higher fractional abundance CHON (17.2 ± 0.1% vs. 14.6 0.4%), CHOS (14.6 4.5% 9.1 3.1%), CHONS (1.6 0.5% 0.5 0.3%) formulas, aromatization average molecular weight, which consistent with stronger terrestrial influence. contrast, high tide, contained greater CHO compounds (75.7 3.8% 66.5 4.1%), humic-like fluorescent C1 component, carboxyl-rich alicyclic molecules (CRAMs), indicating release refractory resuspended sediments. However, variations DOC several optical spectral parameters did not correlate changes salinity height. results principal component analysis revealed different controls on specific fractions that are related variable sources or complexity dynamics underscores necessity elucidating compositions varying levels enhance our understanding cycling estuarine coastal ecosystems.

Язык: Английский

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Effects of riverine nutrient enrichment and sediment reduction on high primary productivity zone in the Yangtze River estuary: historical reconstruction and future perspective

Frontiers in Marine Science, Год журнала: 2025, Номер 12

Опубликована: Март 3, 2025

The high primary productivity zone (HPPZ) of estuaries is known for its flourishing fisheries and active interactions with coastal oceanic ecosystems. However, the spatiotemporal patterns underlying mechanisms that regulate HPPZ remain unclear, especially in face drastic changes riverine inputs. Using 40 years situ monitoring data along Yangtze River estuary, evolution regulated by basin-estuarine-offshore flux fluctuations has been reconstructed past conclusions drawn future developments. Moreover, biological processes influence formation were explored within context estuarine filtration buffering effects. obtained dataset includes chlorophyll a (Chl-a) concentrations multiple environmental factors. results displayed characterized annual average Chl-a concentration 3.6 ± 2.4 μg/L, which driven sufficient light nutrient availability promote phytoplankton blooms. In contrast, inner turbidity exhibits an 1.0 0.7 primarily due to limited inhibiting growth. Meanwhile, outer lower zone, 0.9 1.1 from deficiencies limit Notably, synergistic effect sediment declines eutrophication resulted 6.5 μg/L increment HPPZ’s 3628 km² expansion area extent over years. This significant change attributed increase water transparency resulting reduction transported watershed sea, nitrogen phosphorus discharge. A projection, based on historical total suspended matter nutrients years, suggests will reach 10.5 projected 7,904 2050. study presents first quantification spatial range focusing interaction between materials. These findings offer deeper understanding managing ecological risks large estuaries.

Язык: Английский

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Changes in riverine dissolved organic matter caused by gypsum‐induced flocculation

Journal of Environmental Quality, Год журнала: 2025, Номер unknown

Опубликована: Фев. 10, 2025

Abstract Gypsum (CaSO 4 ·2H 2 O) is increasingly used to bind P soil on agricultural fields, which mitigates eutrophication caused by runoff of excess PO 3− fertilizers into adjacent aquatic environments. also binds dissolved organic matter (DOM) particles. that gets fresh water after field applications may result in enhanced particle formation DOM flocculation and alter C transfer rivers draining catchments. We tested the potential effects gypsum additions cycling adding concentrated solution river before subjecting it controlled mixing increase collisions flocculation. addition increased amount suspended particulate three four times higher than controls without gypsum. The flocs contained a relatively high minerogenic Gypsum‐induced removed colored which, together with removal particles, clarity. associated changes pool did not affect microbial growth or processing, suggesting target labile fraction pool. While acknowledging responses detected our study might depend region, we propose riverine application results either no slightly positive quality should be considered an obstacle for prevention using applications.

Язык: Английский

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Stepwise variations of nutrients and organic matter in the fragmented Changjiang River by two big “dams”: One visible and one invisible

Continental Shelf Research, Год журнала: 2025, Номер unknown, С. 105438 - 105438

Опубликована: Фев. 1, 2025

Язык: Английский

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Optical transformation of riverine colored dissolved organic matter during salt-induced flocculation

Biogeochemistry, Год журнала: 2025, Номер 168(3)

Опубликована: Май 5, 2025

Язык: Английский

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